In modifying and fabricating wafers, semiconductor die, photomasks and flat panel display/microdisplay devices for the semiconductor industry and other industries as well as correcting defects in masks used for processing of semiconductors, it is sometimes necessary to create small holes and other shapes that are relatively deep compared to their diameter or surface area. It is also sometimes necessary to create small holes and shapes relative to other device features with a high positional accuracy. With regard to holes, high aspect ratio holes are difficult to create. Note that, the ratio of the depth to width is referred to as the aspect ratio.
Attempts to overcome the difficulty associated with high aspect ratio structures have been relatively unsuccessful. Generally, these solutions either bore material out of the sample using particle beams such as ion beams, electron beams or laser beams. For example, U.S. Pat. No. 6,403,388 to Birdsley et al. discloses a method of using ion beams for this purpose. Such beam devices are also used to deposit material on the sample surfaces by introducing gasses into the beam. However, there are distinct disadvantages with these solutions.
U.S. Pat. No. 6,827,979, U.S. Pat. No. 6,635,311 as well as U.S. patent application Ser. No. 10/449,685, U.S. patent application Ser. No. 10/442,188, U.S. patent application Ser. No. 10/465,794, U.S. patent application Ser. No. 10/301,843, U.S. patent application Ser. No. 10/261,663 to Mirkin et al. teach methods of using scanning probe microscopes to add material to objects in small dimensions. These teachings show chemical techniques as the mechanisms for the additive process. These teaching do not include the activation of the additive materials by the use of electromagnetic, particle beam or gaseous materials. The use and apparatus of activation means described by the applicants herein results in substantially more versatility in applicant's invention.
U.S. Pat. Nos. 6,737,646 and 6,674,074 to Schwartz disclose adding material to an object by coating a tip and applying that coating to an object with an atomic force microscope. The invention further teaches a chamber for containing gasses. However, the invention has a distinct disadvantage in that at no point is the coating or material activated with an energy device. By including an energy device, the time to add the material to an object is significantly reduced.
When using ion beams to attempt material removal, the ions may imbed themselves in the sample or device to varying depths. As a result, the device becomes unusable because the device properties may be changed by the presence of the imbedded ions. The introduction of gasses into an ion beam also poses additional challenges in containment in and the selection of suitable gasses in the ion beam chamber.
With electron beams, controlling the position of the beam becomes difficult if the sample begins to develop charge. This phenomenon occurs when the electron beam strikes a non-conductive or poorly conductive substrate surface. As a result, the accuracy of this method becomes a serious concern for the end user. The use of such beams can cause uncontrolled damage, which could render the target device unusable. The introduction of gasses into an electron beam also poses challenges in the containment in and the selection of suitable gasses in the electron beam chamber.
With laser light, the size of the hole may be limited by the size of the achievable focus spot. In cases where material modifications smaller than the nominal focus spot are achieved, the depth of removal, and therefore the aspect ratio, is limited Laser light then only becomes a partial solution with limited applications due to the limitations of the focused light beam wavelength.
Additionally, in semiconductor processing and evaluation, physical access to subsurface features may also be needed. A small diameter hole or small area for holes that are not round, is desirable to prevent destruction or damage to features in the device that are adjacent to the hole. None of the prior art solutions are able to achieve this task with a relative degree of accuracy and precision.
Accordingly, a technique that is able to modify a sample such as a semiconductor with high positional accuracy and volumetric control is needed. There is also a need to be able to modify the semiconductor or target device to add material as required by the end user. There is also a need to be able to remove varying levels of materials without greatly affecting adjacent areas. The combination of high aspect ratio features with high positional accuracy, limits the affect to adjacent areas.